Dilute Acid Hydrolysis and Bioconversion of Waste Potato to Ethanol and Yeast Lipid for Evaluating Carbon Flow in Waste Biorefinery.

High quantity of potato wastage from the process and cold storage facilities in India poses serious disposal issues and loss of carbonaceous starches. Waste potato biomass has the potential estimated to be 6.3–7.2 MMT of fermentable sugar equivalent per annum. This study evaluates ethanol and yeast lipid production feasibility using the non-marketable waste potato. For obtaining optimum sugar, the dilute acid hydrolysis was first optimized by one variable at a time (OVAT) approach, and an artificial neural network was formulated to model the hydrolysis process. The optimized variables considered were reaction time, temperature, and acid concentration. The optimum glucose concentration of 55.82 g/L was utilized as a carbon source for ethanol and yeast lipid production by Saccharomyces cerevisiae and Rhodotorula mucilaginosa IIPL32. Ethanol and lipid concentrations of 33.74 and 2.6 g/L were obtained, respectively. The carbon balance of the two processes showed that the flow of net carbon concerning the feedstock was more towards the waste streams. The finding, therefore, proposes that with proper supply chain management, this fermentable carbon can be destined as a co-feed in any existing distillery, or even a separate decentralized system can be envisaged. This study thus investigates the stepwise carbon mapping from the feedstock to the product leading to a cradle to gate carbon flow assessment to understand the net carbon sustainability. [ABSTRACT FROM AUTHOR]